I've been doing some basic audio editing in After Effects, because it's there and convenient. I've found that if I fade the audio in or out, it can sound fine before an uncompressed Quicktime render. Once rendered, the audio at the point of edit has a much steeper ramp up or ramp down, as far as being able to hear it. I keep going back and increasing the duration of the fade, roughly double. I realize that AE is not the best audio app, but maybe I'm missing something. I've noticed a slight falling off of volume in general, but the transitions are more pronounced. When I use Quicktime pro to convert Animation to the H.264 codec, I don't get even half as much loss.

Tools: AE CS3, duel Intel Mac desktop, 4 GB ram, OS 10.4.11

Audio source: bit rate 1411; sample rate 44.1 kHz; format .aif

Rendering to: 44.1 kHz; 16 bit. There is no higher bite rate with the Animation codec, that I can see.

That's one of the things I'm doing. I still would like to know why prior to render I get a sound that's just right, but I'm having to compensate (set a hotter level) to rectify the loss that takes place during render. If I can't get an answer that says "you need to change X", I'll just migrate to a non Adobe application for this task.

^ Good questions. How are you determining the difference, just by ear? What application are you playing the rendered file from? Does the playback application have the same volume settings, same EQ settings etc?

What level are you fading to? After -48dB there is no discernable audio, so fading beyond that level will result in sharper curves than required.

You should be able to render to 48Khz as well. The video codec has no effect on what Quicktime can contain.

To verify the perceived drop in levels, I did the following: The new uncompressed Quicktime movie (with unexceptible audio) was loaded into the After Effects project. I then created a new comp. On the first layer I imported the original comp that the QT movie was rendered from. On the 2nd layer I imported the new QT movie. With the audio levels monitor window open and large enough to clearly see, I alternately played the audio from the two layers and watched the levels meter. The meter showed lower levels in the movie, the 2nd layer.

Andrew, exactly how was your project environment and your test set to render, for example: 48 or 44.1 kHz? When I have a problem in AE, it's usually a single switch or setting that I've overlooked. I sincerely hope that's the case here.

I'm currently rendering at 44.1 kHz for two reasons. Some of the audio is produced with Apple applications that only output at 44.1, and from what I've read, this setting is more 'native' to my computer hardware.

That is correct. I'm not selecting compression for anything at this point. Except for tests, I do all my compression in another application. I also checked to see how the Quicktime render was interpreted. The files are coming back into AE the same as the work space frame rate: 29.97. I don't know how this would matter in audio, but I have seen a file interpreted as 30 not play correctly in a 29.97 comp. Maybe noting this will trigger someone's memory about another setting.

Andrew, exactly how was your project environment and your test set to render, for example: 48 or 44.1 kHz? When I have a problem in AE, it's usually a single switch or setting that I've overlooked. I sincerely hope that's the case here.

I'm currently rendering at 44.1 kHz for two reasons. Some of the audio is produced with Apple applications that only output at 44.1, and from what I've read, this setting is more 'native' to my computer hardware.

I set up that project replicating as much detail as you had provided. The noteable difference: my source file was a 16 bit 48Khz aiff (which was all I had - I always use 48Khz audio because it is native to broadcast video formats like Digital Betacam, and also to DVD.) But my rendered output was 44.1Khz files, and STILL the files look and sound the same as the 48Khz original.

I'm a little unclear about your mention that your source audio has a bitrate of 1411 kbps? Where does that info come from? Are you certain your source audio is not compressed in some way? After Effects doesn't always work well with compressed audio formats, so it would be wise to do your tests using uncompressed source files.

Here's a long answer to the your bite rate question. As kind of a joke, I'm scoring some of my own audio (it's suppose to be humorous). I'm doing this with the help of Apple's Garage Band. The best quality that I can find for exporting from Garage Band is going through iTunes. In iTunes, the kHz and bit rate is shown for each clip. Some tracks that I built in Sound Track (another Apple app) have a different bit rate. All the Garage Band tracks are 1411 kbps. I don't know what significance this could have in this situation, but it has considerable importance with Quicktime movie playback when I'm converting the Animation codec to H.264.

I could understand a lower quality issue more intuitively if it was more manifest when I originally loaded the 44.1 track into AE, verses being more evident after render. However, I hope I'm not the kind of person who struggles with the obvious (for much longer). With two earlier projects with audio from actual musicians, the AE project settings for those were 48 kHz and I never noticed any falloff.

The Reel Montage is a work in progress that is an item of current concern. Just below that are two Pop Star Penalty Round clips that are a combination of in-house folley, voice recording, and Garage Band (44.1kHz). Scroll down to the Near Trailer for a clip that was authored at 48kHz, with audio provided from the previously mentioned outside source. This clip has been degraded by compression by YouTube, and needs to be reloaded. But, the audio probably didn't suffer as much as the video.

As things stand, I think I'll permanently set the AE environment at 48kHz. I thought this would cause needless oversampling, but what do I care if the result is better. It's apparently a requirement in my particular production pipeline.